Electric heating appliance.



T. LIDBERG.

ELECTRIC HEATING APPLIANCE.

APPLICATION FILED JAN-19,1916- Patented Dec. 26,1916.

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UNITED STATES PATENT OFFICE.

'IIODOLE LIDBEBG, OF CHICAGO, ILLINOIS, ASSIGNOR. TO CHICAGO SURGICAL &ELECTRICAL COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

ELECTRIC HEATING APPLIANCE.

Specification of Letters Patent.

Patented Dec. 26, 1916.

To all whom it may concern Be it known that I, TIoboLr LIDBERG, acitizen of the United States, residing at Ohicago, in the county of Cookand State of Illino1s, have invented certain new and useful Improvementsin Electric Heating Appliances, of which the following is aspecification.

My invention relates to improvements in electric heating appliances andhas especial reference to devices of this character, wherewith toproduce and to maintain constant temperature within an area to beheated.

One of the objects of my invention is to provide an appliance especiallyadapted for heating a liquid bath to maintain it at a substantiallyconstant temperature, under varying extraneous atmospheric conditions,and especially adapted for maintaining a water bath at a constanttemperature, within a very small variation, such as used inbacteriological research, in which the culture tubes are required 'to bekept for periods of time at selected temperature, without materialchange.

Another object of my invention is to generally improve appliances ofthis character to render them accurate and reliable; to reduce the costand to simplify their construction.

Other and further objects of my invention will become readily apparent,to persons skilled in the art, from a consideration of the followingdescription when. taken in conjunction with the drawings, wherein Figure1 is an elevation of the appliance and a water bath showing parts insection. Fig. 2 is a transverse section taken on line 22 of Fig. 1. Fig.3 is a transverse section taken on line 3-3 of Fig.1.

In all the views the same reference characters are employed to indicatesimilar parts. In the drawings 5 is a vessel containing a Wvater bath 6,which it is desired to maintain at a constant temperature. The electricheater 7 comprises an electric heating coil 8 wound back and forth uponpins 9 that are driven into a wafer-like disk of insulatingmaterial 10.The heating'unit is placed within a liquid tight envelop or casing 11and surrounded by a suitable mastic insulating mass 12. A verticallextending conductor carrying tube 13 1s secured to the casing 11 bymeans of a nut 14, or in any other suitable manner. Upon the upper endof the tube 13 is a cruciform fitting 15, provided with insulatingbushings 16 and 16'. The tube 13 enters the opening in the extension 17,of the fitting 15, and a lamp socket 18 is screwed into the extension 19of the fitting. An indicating lamp 20 is screwed into the socket 18. Athermo-responsive device 21, for controlling the heater, consists of atube 22, closed at its lower end, as at 23, and secured to the tube 13,as by the clamp 24. The bushing 25, of insulatingmaterial serves as aclosure for the upper end of the tube 22. From the bushing 25 issuspended a rod 26 which is only slightly shorter than the entire lengthof the tube 22. The screw threaded portion 27, of the rod, makeselectrical contact with the screw threaded bushing 28, in which the wire49 is to be inserted and clamped by the screw 30. A similar terminalbushing 31, is diametrically opposite the bushing 28, and is held inplace by a screw 32 which supports a bracket 33. A bell-crank lever 34is pivoted to the bracket 33, as at 35, and is provided with a laterallyextending arm 36 and with a downwardly extending arm 37, which lattercarries a contact 38. A spring 39 yieldingly maintains the arm 37 inposition substantiall central of the tube. 22. The normal position ofthe contact 38 of the arm 37, however, is determined by an adjustingscrew 40 which asses centrally through the bushing 25 and 1s providedwith a reduced end, 41,-which engages the arm 36 of the lever 34. Thescrew 40 is threaded into an insert metallic bushing 42, which issecuredaxially'of the bushing 25. A check nut 43 holds the screw 40 inadjusted position and athumb turned, knurled head 44 is the means bywhich the screw may be rotated for the purpose of adjusting the positionof the contact 38, on the arm 34.

On the lower end of the rod 26, is a. lug 45 to which a thermostaticexpansion bar 46 is secured, as by screws or rivets 47. The bar 46carries on its free'end a contact 48, which electricallyconnects withthe contact '38, on the arm 34.

Wires 49 and 50 are intended for connection with a suitable source ofelectric current. The wire 49 is inserted in an opening in the bushingconnector 28 and clamped in place by screw 30. The wire 50 is connectedto the vertically extending wire 51, as at 52, the downwardly extendingbranch being connected to the terminal 53, of the heater wire 8. Theupwardly extending branch 51 of wire 51 is connected to one terminal ofthe socket 18 in which the signal lamp 20 is contained. A wire 55 isconnected at one end in the bushing connector 31, of the regulator andat its other end to a vertical wire 52 positioned Within the tube 13.The Wire 52 is connected at its lower end to the terminal 53 of theheating coil 8, and its upper end 53, is connected to a terminal of thelamp socket 18.

The operation of the device is as follows z-VVhen the heater 7 and theregulator 21 are placed in a water bath, 6, as shown in Fig. 1, thecontacts 38 and 48 are together and the circuit is thereby closedthrough the heater conductor 8 and the lamp20 in parallel. The circuitconnection between the contacts 38 and 4&8 will remain closed until thetemperature of the water 6 has been raised sufficiently to cause the bar46 to expand laterally and break connection between said contacts. Atthis time the lamp 20 will be extinguished and the current will bewithdrawn from the heating coil 8. When the temperature of the bathdecreases, or

tends to decrease, the bar 46 will contract into its original positionuntil connection 1s again established between the contacts 38' and 48and the circuit will be thereby closed and the current will again Howthrough the heater coil 8 to raise the temperature of the water. Thetemperature of the waterbath may be varied by turning the screw 40. Whenit is turned to the left, the screw end 41 is raised so that the contact38 may be moved further over toward the opposite side of the tube 22 bythe spring 39. Contact 48, on the expansion bar 46, will then breakconnection with contact 38 at a lower temperature. The spring 39 holdsthe arm 36 of lever-34z at all times in contact with the end of screw 40so that upward and downward movement of the screw is converted intosidewise movement of contact 38. lit a higher temperature in the bath 6is desired, the screw is manually rotated to the right and the contact38 is moved over toward the left, and the expansion bar is thus putunder greater tension, requiring higher temperature to cause it to breakconnection between contacts 38 and 48.

The tube 22 is substantially air tight and, therefore, the air withinthe tube, that is heated by the water cannot escape and the expansionbar 46 is therefore heated to a uniform temperature, substantiallythroughout its entire. length, partly bycirculation of air within thetube, thereby rendering it very sensitive to changes of heat, andcausing it to respond instantly to the slightest variation thereof,

naoaeea The casing 11, containing the heater 10,

is made fiat and of large diameter so as to serve as a base support forthe device, and resting upon the floor of the container 5 it is in thebest location for the purpose of heating the liquid contained therein.

Having described my invention, what I claim is 1. Tn a portable electricheater, the combination of a relatively broad flat casing, a heatingcoil inclosed therein, a conductor carrying tube projecting upwardlyfrom: the casing, and a thermostatic controller supported by the tube.

2. Tn a portable electric heater, the combination of a relatively broadflat casing, a heating coil inclosed therein, a conductor carrying tubeprojecting upwardly from the casing, a substantially air-tight tubesupported by the first mentioned tube, and a thermostatic controllercontained within the last mentioned tube.

3. In a portable electric heater, the combination of a relatively broadfiat casing, a heating coil inclosed therein, a conductor carrying tubeprojecting upwardly from the casing, -a substantially air-tight tube supported by the first mentioned tube, and e2rtending downwardly to a pointadjacent the flat casing, a thermostatic controller contained within thelast mentioned tube, and an electric circuit connecting the heating coiland thermostatic controller in series.

1. A device of the character described comprising a heater provided witha relatively broad flat heating element; a vertically disposed tubeextending therefrom; an indicating lamp, mounted on the top of the tube;in combination with, a thermoresponsive device, for controlling the heatproduced by said heater, said thermo-responsive device comprising aclosed tube, parallel with the heater tube and connected thereto; anexpansion bar carrying a contact, and a cooperating contact, within thelatter tube; a screw at the top of the latter tube to adjust theposition of the coiiperating contact, and wires passing through theheater tube to connect said thermo-responsive device and lamp in circuitwith said heater.

5. A. device of the character described comprising an electric heaterelement; a vertically disposed tube connected .therewith; a cruciformfitting on the upper end of the tube a socket for a lamp mounted on onearm of the fitting, conducting wires extending through the horizontalarms of the fitting; branch wires in said tube connecting said lamp andheater element in parallel connecting said switch in series with said1.30

heater and said lamp to extinguish the lamp when circuit through theheater is thereby opened.

6. A device of the character described comprising a heater provided witha heating element; a tube extending therefrom; an indicating lampmounted on the tube; in combination with, a thermo-responsive device,for controlling the heat produced by said heater, said thermo-responsivedevice comprising a closed tube, connected with the heater tube; anexpansion bar carrying a contact, and a cooperating contact, within thelatter tube; a screw on the top of the latter tube to adjust theposition of the cooperating contacts, and wires passing through theheater tube to connect said thermo-responsive device and lamp in circuitwith said heater.

7. A device of the character described comprising a heater provided witha heating element; a tube extending therefrom;

an indicating lamp, mounted on the tube;

in combination w1th, a thermo-responsive device, for controlling theheat produced by said heater, said therr'no-responsive device comprisinga closed chamber, connected with the heater tube; an expansible membercarrying a contact,'and a cooperating contact, within the chamber; meansprojecting outside of the chamber to adjust the position of thecooperating contact, and wires passing through the heater tube toconnect said thermo-responsive device and lamp in. circuit with saidheater.

In testimony whereof I hereunto set my hand in the presence of twosubscribing wit nesses.

TIODOLF LIDBERG. In the presence of- FoRfiE BAIN, MARY F. ALLEN.

